Electric vehicles or hybrid vehicles are well known from the prior art. Said vehicles are typically driven by electric machines, which in turn are supplied with power by an energy storage cell, for example a high-voltage battery. To that end, the energy storage cell has to be charged regularly and is connected to an external power supply, e.g. a charging station, for this purpose. In some cases, voltage doubling, where the voltage of the external power supply is doubled, is required in order to provide an adequate charging voltage for the energy storage cell. Said voltage doubling is performed, in particular, by a charging apparatus, which is interconnected between the energy storage cell and the external power supply during charging. Simple voltage doubling can be realized here by means of a simple charge pump, for example.
It is further known from the prior art to adjust the charging voltage during charging. A voltage adjustment of this kind is generally carried out by a DC voltage converter.